An image captured by the WorldView-2 satellite last year shows Alaska's Cleveland Volcano. The summit of the volcano is mostly snow-covered, and the growing lava dome is seen as the dark feature in the center of the image.

New satellite imagery of the 5,676-foot peak, located about 940 miles southwest of Anchorage in Alaska's remote Aleutian islands, shows a new, bulging lava dome forming in the volcano's summit crater, suggesting a buildup of gas pressure.

Even though the volcano is in an uninhabited area, an eruption could still cause a big mess. According to CNN, some 90 percent of air freight from Asia to Europe and North America passes over Alaska, along with hundreds of commercial flights.